JPH07266561A - Ink jet recording and recorder - Google Patents

Abstract

PURPOSE:To provide a noiseless and blocking-free ink jet recording system and a recorder. CONSTITUTION:A recording head is equipped with a liquid chamber 2 containing an electroviscous ink, the liquid chamber 2 has a slit-form opening from which ink drops are discharged. A plurality of pairs of control electrodes 1A, 1B are extended toward the opening in the opposing insides of the liquid chamber 2. Voltage of different polarity is applied alternately to plurality of pairs of control electrodes 1A, 1B and an ink wall of high viscosity are formed between each pair of control electrodes and a channel is formed between the walls though which ink flow. If pressure is applied to the ink inside each channel 8D selectively depending on image information, ink drops are discharged from the opening. If no voltage is applied to the control electrodes 1A, 1B, ink walls and channels disappear and the liquid chamber is not compartmentalized and remains in a communicating condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording system and a recording apparatus adopting this recording system, and more particularly to an ink jet recording system used in an ink jet printer or the like and its recording device.

[0002]

2. Description of the Related Art Recently, in the field of low-priced and small-sized printers, so-called serial ink jet printers in which an ink jet head runs along the width direction of a paper and a paper is fed every time one line is recorded are popular. I am doing it. The inkjet method has the advantages that the device can be downsized, the pixel formation speed is high, and the running cost is low, but on the other hand, printing becomes unstable due to clogging of the head, and the pixel density is high. There are disadvantages such as being unsuitable for gradation recording. In particular, the problem of head clogging is important, and it is said that this is a main factor that delays the practical use of the inkjet method compared to other recording methods. Currently, in serial-type inkjet printers, measures such as capping the head when not in use, performing preliminary ejection when the printer is started up, and cleaning the print head when it is clogged are being implemented.
Even if these measures are taken, the so-called line inkjet printer, which arranges a plurality of heads in a line and prints one line at the same time, has not yet been put into practical use.

The cause of clogging of the head is generally attributed to the nozzle. Usually, since the nozzle diameter of an inkjet head is about several hundreds of μm, there is a problem that when ink is dried, it is very likely to be clogged. Also,
When the ink dries, there is a possibility that the quality of printing may deteriorate due to the deterioration of the ink even if the ink is not clogged.

Therefore, an ink jet recording method without a nozzle has been devised. There is a "slit-jet recording method" in which a head is composed of two slit-shaped flat plates and ink is drawn out by electrostatic attraction force to record, Ichinose, Ohba, Jigakuron (C) J66-C (Showa 58). . This is slit width 100μm, bias 3kV, signal pulse 300V
Drive with.

In Japanese Patent Laid-Open No. 63-121157, a high temperature melting ink is used to melt the ink when recording,
An acoustic ink printer that ejects ink by an acoustic beam is proposed, and in Japanese Patent Publication No. 2-40512, the ink transfer body is used as one electrode to utilize the electroosmosis of the liquid ink to the dielectric according to the applied signal voltage. The amount of liquid ink deposited on the surface of the ink transfer body is controlled by the signal voltage applied between one electrode and the other electrode, and this deposited ink is transferred and deposited on the recording surface to form an ink image corresponding to the signal voltage. It proposes a recording method and a recording device for recording.

Recently, a new ink jet recording method using an electrorheological fluid (Fiscal year 2002, Japan Printing Society, No. 8)
4th Spring Research Presentation, University of Yamanashi) is being studied. In this recording method, an electrorheological fluid is used as the ink, and an electric field is turned on / off in a pressurized state to cause the ink itself to perform a valve action to control the inkjet.

Further, in Japanese Patent Laid-Open No. 57-75866, an ink having an electrorheological effect is used, and a voltage is applied between one or more pairs of electrodes provided in a nozzle portion to eject ink droplets. There is disclosed a recording apparatus for recording with high resolution by reducing the nozzle size.

[0008]

It has been pointed out that the conventional ink jet recording system and the recording apparatus therefor require a fixed nozzle, which causes clogging. Due to this clogging, it is difficult to arrange the recording heads substantially in a line. The cause of the clogging of the head is in the nozzle, and generally, since the nozzle diameter of the inkjet head is about several hundred μm, there is a problem that the clogging is likely to occur when the ink is dried.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a nozzleless ink jet recording system and a recording apparatus therefor, which does not cause clogging.

[0010]

According to the present invention, there are provided a plurality of first channels through which ink having an electrorheological effect flows, and first and second inner surfaces opposed to each other. Housing housing ink supplied through the channels and a slit-shaped opening for discharging the stored ink, and a predetermined array facing the first and second surfaces, respectively. And a plurality of pairs of control electrodes arranged by a voltage applying means for applying a drive voltage to the control electrode pairs to form an ink wall by increasing the viscosity of the ink between the control electrode pairs to which the voltage is applied. A voltage applying unit that communicates with the first channel by an adjacent ink wall to generate a second channel that allows the ink to flow to the opening; and a voltage applying unit that is provided in each of the first channels,
Pressurizing means for applying a pressure to the ink in the corresponding first channel according to the recording information and ejecting the ink in the corresponding second channel as an ink droplet from the opening. An inkjet recording device is provided.

Further, according to the present invention, the first channel has a plurality of first channels through which the ink exhibiting the electrorheological effect flows, and the first and second inner surfaces facing each other. And a housing formed with a slit-shaped opening for discharging the stored ink, and the first and second surfaces are arranged in a predetermined arrangement so as to face each other. A plurality of pairs of control electrodes and voltage applying means for applying a drive voltage to the control electrode pairs to generate mutually adjacent electric fields in different directions, and increasing the viscosity of the ink in the area to which the electric field is applied A voltage applying unit that forms a wall and communicates with the first channel by an adjacent ink wall to generate a second channel that allows the ink to flow to the opening, and a voltage applying unit that is provided in each of the first channel. And pressurizing means for applying pressure to the ink in the corresponding first channel according to the recorded information and ejecting the ink in the corresponding second channel as an ink droplet from the opening. An inkjet recording device is provided.

Further, according to the present invention, in the liquid chamber containing the ink exhibiting the electrorheological effect, an electric field is generated at a plurality of portions in the liquid chamber to increase the viscosity of the ink, thereby forming an ink wall. A channel through which the ink circulates is generated between the ink walls, and pressure is applied to the ink selectively supplied to the channel according to the recording information to generate an ink droplet from the corresponding channel outside the liquid chamber. An inkjet method is provided that comprises a step of ejecting.

[0013]

In the recording head of the present invention, the slit-shaped opening is formed during non-recording, and the viscosity of the ink itself is changed during recording to dynamically control the formation of the ink ejection channel, and the fixed channel wall and nozzle or orifice are used. Does not need

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ink recording system and recording apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

The structure of an ink jet type recording head according to an embodiment of the present invention is schematically shown in FIG. The head shown in FIG. 1 can simultaneously record a plurality of pixels corresponding to one line by one head, as described later in detail.

The recording head has an ink supply port 1 at one end thereof.
Ink (viscosity μ = μ1) is supplied from No. 4 and ink is ejected from the ink ejection port 15 at the other end. The housing of this recording head is formed in a flat plate shape extending in the direction of one line as shown in FIGS. 2 and 3, and the ink supplied along the ink supply path flows into the housing. The first channel 5, the recording drive unit 4 that applies the ejection pressure to the ink, the second channel 3 that the ink to which the ejection pressure is applied flow out, and the liquid chamber 2 that collects the ink and sorts the ejected droplet ink It is provided.

In the liquid chamber 2, there is provided a control electrode 1 for controlling the ejection of ink based on the ER effect described later,
The control electrodes 1 are arranged at a pixel pitch along the one line direction as shown in FIG. In addition, the recording drive unit 4
Is provided with a piezo element 6 that applies an ejection pressure to the ink. The inside of the head is filled with ink, and the ejection port 15 at the tip of the head is balanced with the atmospheric pressure by the surface tension of the ink.

As shown in FIG. 2, the inside of the first channel 5 is divided by a channel wall 7A and is divided into a plurality of channels 8A. This channel 8A is provided corresponding to the number of recording pixels of this recording head. Since the recording head according to the embodiment of the present invention is an eight-pixel head, eight channels 8A are provided. Further, the recording drive unit 2 includes
A channel wall 7B extending from the channel wall 7A is provided, and is separated by the channel wall 7B into channels 8B communicating with the channels 8A. A piezo element 6 is provided in each of the channels 8B. Further, the inside of the second channel 3 is also divided by the flow channel wall 7C extending from the flow channel wall 7B, and is divided into a plurality of channels 8C communicating with the channel 8B.

As shown in FIG. 3, the liquid chamber 2 is formed in a common space which is not divided by the flow path wall, but is divided into a plurality of channels 8D by utilizing the ER effect as described later. 7C on the flat plates 12A and 12B defining the liquid chamber 2 so that the control electrodes 1A and 1B for facing each other face each other.
It is provided to extend from. Therefore, as shown in FIG. 3, the front surface of the recording head has two flat plates: 12A,
The liquid chamber 2 is formed in a slit-shaped ejection opening composed of 12B and is filled with ink.

Since the channel 8D is defined by the two sets of control electrodes 1A and 1B, a pair of control electrodes 1A and 1B is provided at both ends of the head, and this recording head has a total of 9 (= 8 + 1). ) A set of control electrodes 1A, 1B is provided.

In the recording head shown in FIG. 1, ink utilizing the electrorheological (ER) effect is used for recording. This ink uses an insulating oil-based fluid as a dispersion medium and contains about 20 microparticle powders of a pigment such as carbon black.
% (Volume ratio). As the dispersion medium, kerosene, silicone oil, cyclohexane or the like is used, but almost any fluid can be used as long as it is insulating. Further, an electrorheological fluid colored with a dye can be used. In addition, heat treatment of resins such as vinyl chloride, epoxy, polystyrene, and polyvinyl acetate creates carbon properties on the surface of fine particles of the resin, and the electrorheological fluid based on carbon particles or polystyrene is used as the particle nucleus to impart electrical conductivity to the surface. For fixing metal or organic conductor, carbon, polyacetylene, etc. for coating, an electrorheological fluid of triple structure in which the outermost surface is coated with an insulator such as vinyl chloride or silica, and polyoxyalkylene chain particles as dispersed particles for ion exchange resin An electrorheological fluid such as the one described above can also be used.

The electrorheological fluid is dispersed in the fluid between the control electrodes 1A and 1B facing each other as shown in FIG. 4 (a), and the fine particles 11 are applied with a voltage as shown in FIG. 4 (b). , Is polarized by the electric field generated between the electrodes 1A and 1B. This polarization creates a force of attracting the particles to each other, and the particles are arranged in a beaded pattern between the electrodes 1A and 1B. Since the particle chains hinder the fluid flow, the fluid has an apparent viscosity increase. This is called the ER effect (Winslow effect). The relationship between the electric field strength and the apparent viscosity is shown in FIG. As is clear from the graph of FIG. 4, the viscosity does not change so much when the electric field strength is 0 to 0.7 kV / mm, but when the electric field strength is 0.7 kV / mm or more, the viscosity increases in proportion to the electric field strength. To do.

In the recording head of the present invention, channel formation in the recording head is controlled by utilizing the ER effect. That is, no voltage is applied to the electrodes at the time of non-recording.
As shown in, there is no limit in the liquid chamber, and
The R ink is free to move. On the other hand, when a voltage is applied to the pair of control electrodes 1A and 1B facing each other, the clay of the ink between them becomes high, and the wall surface 10 of the ink is substantially formed. Here, when a voltage is applied to the two sets of control electrodes 1A and 1B adjacent to each other, the channel 8D is substantially formed by the wall surface 10 of the ink as shown in FIG. That is, when the [i] th pixel is recorded as shown in FIG.
-1) th and (i) th upper and lower two sets of control electrodes 1A, 1
A voltage is applied to B. (Steps 61, 62) As a result, the (i-1) th and (i) th control electrodes 1A, 1B
In the ER ink between them, the ER effect occurs, and the viscosity becomes much higher than that when no voltage is applied. Therefore, at the positions of the (i-1) th and (i) th control electrodes 1A and 1B and on the flat plate 12
Between A and 12B, one end is connected to the channel 8C and the other end reaches the opening. The ink wall 10 (viscosity μ = μ2;
μ1 <μ2) is formed, and the [i] th channel 8D is formed. At this time, when the piezo element 6 of the recording drive unit 4 upstream of the channel 8D is driven according to the recording information and pressure is applied to the ink of the corresponding channel 8B in the recording drive unit 4, the flow path walls 7A and The ink is pushed along the channel formed by the ink wall 10, and the ink droplet is ejected from the opening of the [i] th channel. (Step 63) After the ink droplet 9 is ejected,
By turning off the voltage of the (i-1) th and (i) th control electrodes 1A and 1B, the ink wall 10 is reduced and the state shown in FIG. 6 is restored. (Steps 64, 65) In this embodiment, when the voltage is off (E = 0 kV / mm), the viscosity μ = μ1 = 8 dPa · s, and when the voltage is on (E = 4 kV / m).
m) is set so that the viscosity μ = μ2 = 40 dPa · s.

The following is a summary of the above recording operation.

1. A voltage is applied to the (i-1) th and (i) th control electrodes 1A and 1B to form the [i] th channel 8D.

2. Next, pressure is applied to the [i] th channel 8D to eject the ink droplet 9.

3. The voltage of the control electrodes 1A and 1B is turned off to reduce the [i] th channel 8D.

By selectively driving the ink viscosity control electrode according to the recording pixel in this way, the viscosity of the ink can be changed to form a wall by the ink itself to dynamically form an ink channel. . Further, in this recording head, there is no fine partition wall fixed in the liquid chamber at the time of non-printing, and the opening is slit-shaped and very wide with respect to the opening corresponding to the pixel. Even if the ink is dried, clogging is unlikely to occur, and even if the ink is deteriorated due to the drying, it is less likely to be affected.

The recording head described above is manufactured as follows.

A mask pattern as shown in FIG. 9 is superposed on the photosensitive glass substrate 34, exposed, and developed,
In the non-exposed area, the glass is eluted to form a groove, and in the exposed area, the glass is cured and is not eluted and remains as it is. By this process, eight liquid chambers 2 each having a depth of 100 μm, channels 3, pressure chambers of the recording drive unit 4, that is, channels 8B, channels 5 and ink supply chambers 31 are formed. The length from the end of the flow path wall of the liquid chamber 2 to the end of the substrate is 3
The width is 100 mm and the width is 100 mm. The channel 5 and the channel 3 have a width of 100 μm and a length of 2 mm. The pressure chamber 8B is a circle having a diameter of 8 mm. Ink supply chamber 31
Has a length of 4 mm and a width of 100 mm.

Next, one electrode of the pair of control electrodes 1A and 1B shown in FIG. 9A is set in the liquid chamber 2 of the glass substrate 34 so that the flow path wall 7C extends to the end of the liquid chamber. To form. Aluminum is uniformly deposited to a thickness of 2 μm on the liquid chamber surface of the substrate 34 shown in FIG. 9A by vapor deposition, and then photoresist is uniformly applied. Next, exposure is performed after aligning the mask pattern shown by the diagonal lines in FIG. 9B so as to be in the position shown in FIG. 9B in the liquid chamber. This is developed, and the photoresist is removed leaving only the shaded portion in FIG. 9 (b). Aluminum is eluted and removed using the photoresist as a mask to form the pattern of the control electrode 1 shown in FIG. 9B.

Next, as shown in FIG. 9C, another substrate 3
5, a hole having a diameter of 10 mm and a rectangular hole having a length of 4 mm and a width of 100 mm are formed by machining. The control electrode 1 forming a pair with the electrode 1 shown in FIG. 9 (b) in the above-described process on the substrate 35 so as to be aligned with the electrode pattern previously formed.
Are formed as shown in FIG. The piezo element 6 is bonded to the hole opening of the substrate 34 shown in FIG. 10 with an adhesive. The piezo element 6 is a piezoelectric ceramic element in which electrodes are provided on the upper and lower surfaces with a diameter of 8 mm and a thickness of 0.5 mm.
It is bonded with a conductive adhesive so as to be concentric with the stainless disk 42 having a thickness of 2 mm and a thickness of 0.2 mm. This substrate 35 and FIG.
The substrate 34 shown in (b) is aligned and bonded. The stainless disk 42 of each piezo element 6 is grounded, the electrode on the surface of the ceramic element 6 which is not bonded is connected to a piezo element drive circuit (not shown), and the top plate of the ink supply chamber is It is completed by attaching the supply port 43.

Next, a recording apparatus incorporating the recording head shown in FIGS. 1, 2 and 3 will be described with reference to FIG.

The recording apparatus as shown in FIG.
The recording head 114, the sensor 116, the platen roller 117, and the piezo element drive controller (not shown) shown in FIG. Recording medium 11 such as paper from the left side of FIG.
When the recording medium 115 is conveyed by the platen roller 117 when the sensor 116 detects that 5 is set in the apparatus, the recording head 14 is driven and the recording medium 115 is driven.
The image is recorded on.

FIG. 12 shows the structure of a control unit for controlling the recording apparatus shown in FIG. As shown in FIG. 12, the control unit is a CPU 11 that controls the entire control unit.
8, a RAM 119 used as a work area and the like, a ROM 120 in which control programs and data are stored, and an image memory 12 in which recorded images transferred from the outside are stored
1. A recording control unit 12 that executes overall control for recording
2. Ink wall control unit 123 that controls the formation and disappearance of the ink wall and the pressure of the liquid chamber 2, a viscosity control unit 124 that applies a drive voltage to the control electrodes 1A and 1B in response to a signal from the ink wall control unit 123, and an ink droplet. A recording drive unit 125 that controls the voltage application to the piezo element 6 that generates a driving force for ejecting the recording medium, a conveyance control unit 126 that controls the conveyance of the recording medium, and a sensor 127 that detects the position of the recording medium 115. ing.

The operation of the recording apparatus shown in FIG. 12 will be described with reference to the drive timing charts in the recording operation shown in FIGS. 13 and 14. 13 and 14 show different operation modes.

FIG. 13 shows an operation mode of mode A. When the power source of the recording apparatus is turned on as shown in FIG. 13A, the recording control section 122 operates and the ink wall control section 123.
From this, a viscosity control signal as shown in FIG. 13C is given to the viscosity control unit 124. Therefore, a voltage is applied to the pair of control electrodes 1A and 1B of the recording head, and the operation described above forms the channel 8D corresponding to the recording pixel. When the recording medium 115 is set in the apparatus by the sensor 127, the effective recording time signal shown in FIG. 13B is given to the recording control unit 122. The period in which the effective recording time signal is given indicates the recording time from when the recording medium 115 is set in the apparatus and recording is started to when recording is completed. FIG. 13 generated by the recording control unit 122
In response to the one-line period signal shown in (d), the piezo drive signal is given from the recording drive section 125 to the piezo element 6 as shown in FIG. 13 (e), and an image is recorded line by line. Even if all recording is completed, the viscosity control time signal shown in FIG. 13C does not change, and the ink wall is held in the recording head while the power of the recording apparatus is ON. Then, when the power of the recording apparatus is turned off, the viscosity control time signal is also turned off accordingly, and the ink wall of the recording head is removed.

Next, the recording operation in the mode B shown in FIG. 14 will be described. The way of handling the viscosity control time signal is different between this mode B and the above-mentioned mode A. In mode A, the viscosity control is executed by linking to the power supply of the printing apparatus, whereas in mode B, the viscosity control is executed by linking with the effective recording time. Even if the power of the recording apparatus is turned on as shown in FIG. 14A, the viscosity control time signal shown in FIG. 14C does not change, and the recording medium is set in the apparatus by the detection signal from the sensor 127. When it is confirmed that the recording has been performed, a recordable signal is sent to the recording control unit 122 described later. Recording control unit 1
As shown in FIG. 14C, 12 turns on the viscosity control time signal before the actual recording is started to form a channel by the ink wall, and then the effective recording time signal becomes O.
While N, in response to the 1-line cycle signal shown in FIG. 14D, a piezo drive signal is generated as shown in 14E, and recording is executed. After the recording is completed, the viscosity control time signal is turned off, the ink wall is opened, and the initial state is restored.

When recording is performed in mode A, the viscosity control time signal is switched only once, so that the recording control circuit can be simplified, but ink (= electrorheological fluid)
Since the voltage is always applied to, the deterioration becomes faster than the case where the voltage is applied intermittently. On the contrary, when the printing is performed in the mode B, the viscosity control signal is frequently switched, so that the recording control circuit is slightly complicated, but the voltage is not applied to the ink during the non-recording even when the power of the recording apparatus is turned on. Therefore, deterioration can be suppressed.

The case of executing recording in the above-mentioned mode B will be described with reference to FIGS. 14 and 12.

The CPU 118 reads the control program and the control data from the ROM 120 as needed and executes the control program. First, when the sensor 127 detects that the recording medium is set at a predetermined position, a channel is formed in the recording head.

First, a channel forming signal is sent from the CPU 118 to the ink wall controller 123 via the recording controller 122. The ink wall control unit 123 sends a control signal to the viscosity control unit 124, and the viscosity control unit 124 generates a voltage to be applied to the control electrodes 1A and 1B by a method described later and drives the control electrodes 1A and 1B to drive the channel. To form.

The CPU 118 reads from the image memory 121 to 1
The print data for the line is read and sent to the print control unit 122. The recording control unit 122 sends pixel data to be recorded and a 1-line cycle signal to the recording driving unit 125. In synchronization with the recording cycle of one line, the recording drive unit 125 drives the piezo element 6 of the channel 8D corresponding to the pixel to be recorded to eject ink droplets. When the recording for one line is completed, the data of the next line is read and the same operation is repeated to form an image.

When the recording of all data is completed, the CPU 11
8 sends a channel erasing signal to the ink wall controller 123 via the recording controller 122. The ink wall control unit 123
A control signal is sent to the viscosity control unit 124,
Turns off the drive voltage to erase the channel of the recording head.

Next, when the recording medium 115 comes in, the channel formation of the recording head is repeated again. The recording operation in mode A is also the same as that described above except that the channel formation of the recording head is performed when the power of the recording apparatus is turned on and the channel disappears when the power is turned off.

FIG. 15 shows an example of a circuit for applying a voltage to the control electrodes 1A and 1B, and FIG. 16 shows a timing chart of the operation of the circuit shown in FIG. In the circuit shown in FIG. 15, Vh is a high voltage source (+ 100V) applied to the control electrodes 1A and 1B, and VhGN
D is the high voltage ground. A resistor R1 and a transistor TR are connected between the voltage source Vh and the ground VhGND.
A series circuit of the collector and the emitter of 1 is connected, and a series circuit of the collector and the emitter of the resistor R2 and the transistor TR2 is connected. Transistor TR
The bases of 1 and TR2 are AND circuits AND1 and A, respectively.
The output side of ND2 is connected. This AND circuit AN
The Enable signal is input to the input side of D1 and AND2, and the set Q output and reset Q output of the flip-flop FF are input. Further, the clock CLK is input and the reset output is input to the input side of the flip-flop FF. Where clock CLK
Is the basic clock of this circuit as shown in FIG. 16 (a), and the Enable signal is a control signal for applying a voltage to the control electrodes 1A and 1B as shown in FIG. 16 (b). ) And 14 (c) correspond to the viscosity control time signal.

In the circuit shown in FIG. 15, the circuit shown in FIG.
When the clock CLK shown in is input to the flip-flop FF, the flip-flop F rises at the rising edge of the clock CLK.
From F, the set output and the reset output are AND circuits A
It is input to ND1 and AND2. Here, FIG. 16B
When the Enable signal shown in is input to the AND circuits AND1 and AND2, the AND circuits AND1 and AND2
From, the output signals shown in FIGS. 16C and 16D are given to the transistors TR1 and TR2, respectively. Therefore, the output signals OUTPUT1 and OUTPUT2 are output from this circuit. These output signals OUTPUT1 and OUTPUT2 are shown in FIG.
As shown in the timing charts of (e) and FIG. 16 (f), H and L are repeated, and their phases are shifted by a half cycle. Therefore, the potential difference between the output signals OUTPUT1 and OUTPUT2 is equal to the output signal OUTPUT shown in FIG.
And a rectangular wave in which the voltage + Vh and the voltage -Vh are alternately repeated.

Output signal OUTPUT1 shown in FIG. 16 (e)
Are supplied to the even-numbered control electrodes 1B provided on the lower flat plate 12B and the odd-numbered control electrodes 1A provided on the upper flat plate 12A, and the output signal OUTPUT2 is provided to the lower flat plate 112B. When the odd-numbered control electrodes 1B and the even-numbered control electrodes 1A provided on the upper flat plate 12A are supplied, the viscosity distribution in the recording head is
It is changed as shown in FIG. FIG. 17 (a) is the same as FIG.
6 shows the viscosity distribution when t = t1 in the timing chart of FIG. 6, and FIG.
The viscosity distribution at t2 is shown. Also, FIG. 17 (c)
Shows a viscosity distribution when a negative voltage is applied to the control electrode 1B provided on the lower flat plate 12B and a positive voltage is applied to the control electrode 1A provided on the upper flat plate 12A. (2j) and (j ≧ 1) of the control electrodes 1A and 1B are
The even-numbered control electrodes are (2j−1), (2j + 1),
(J ≧ 1) indicates odd-numbered control electrodes.

In the recording head of the present invention, FIG.
As shown in, the output signals are applied so that the polarities are different between the upper and lower sides and the left and right sides of the control electrodes 1A and 1B. FIG. 16 (e)
The output signal OUTPUT1 shown in (2j) is the lower control electrode 1B and the (2j + 1) th upper control electrode 1A.
Applied to the output signal OUTPUT2 shown in FIG.
Is the (2j) th upper control electrode 1A and (2j +
1) The lower control electrode 1B1w is applied. By thus applying a voltage to the control electrodes 1A and 1B, the viscosity distribution of the ER ink is as shown in FIG. 17A, the center of the channel has a low viscosity, and the vicinities thereof have a high viscosity. A portion is defined by a channel, and ink is ejected by impulsively applying pressure to the ink in this channel. This is
Similarly, at time t = t2 shown in FIG. 7, a voltage signal is applied as shown in FIG. 17B to form a channel.

However, in a recording head to which the method of the present invention is not applied, for example, when the upper electrode is applied to (+) and the lower electrode is applied to (-) as shown in FIG.
j) th lower control electrode 1B, (2j + 1) th upper control electrode 1A, and (2j) th upper control electrode 1
Since a potential difference is generated between A and the (2j + 1) th lower control electrode 1B, in a high-resolution recording head in which the space between the control electrodes is narrow, crosstalk occurs between adjacent electrodes, and the center of the channel has a viscosity. It becomes too high to eject ink droplets well.

A method of applying an AC drive signal to the control electrodes 1A and 1B will be described with reference to FIG. In this embodiment, an alternating current of 50 V and 500 Hz is used as the alternating current drive signal. The AC drive signal shown in FIG.
The phase is shifted by π from the AC drive signal shown in (b), and the AC drive signal shown in FIG. 18A has the (2j) th lower control electrode 1B and the (2j + 1) th upper control. The AC drive signal applied to the electrode 1A and shown in FIG. 18 (b) is the (2j) th upper control electrode 1A and (2j + 1).
The second lower control electrode 1Blw is applied. FIG. 19
As shown in (a), at the peak time, a potential difference of about 100 V is generated between the upper and lower control electrodes 1A and 1B, and the viscosity distribution in the recording head is as shown in FIG.
As shown in (b).

FIG. 19B shows the piezo element driving timing for ejecting ink droplets in response to the voltage application to the viscosity control electrode shown in FIG. 19A. Here, FIG. 19A shows (2) in the viscosity distribution of FIG.
19 shows a time change of the voltage between the j) th upper control electrode 1A and the (2j) th lower control electrode 1B, and FIG.
(B) shows the timing for driving the piezo element 6. As shown in FIG. 19A, the control electrodes 1A, 1B
The voltage between them is synchronized with the one-line recording period of the recording pixel, and in this embodiment, the piezoelectric element 6 is driven when the voltage between the control electrodes 1A and 1B changes from (-) to (+) at 0V. Voltage is being applied.

The effect of the phase shift when an AC drive signal is applied between the control electrodes 1A and 1B will be described with reference to FIG. 20 (a), 20 (b) and 20 (c) are both shown in FIG.
7A shows the time change of the voltage between the (2j) th upper control electrode 1A and the (2j) th lower control electrode 1B in the viscosity distribution of 7 (a). Also, these FIG.
(A), (b) and (c) are equal to the time variation of the voltage between the (2j) th upper control electrode 1A and the (2j + 1) th upper control electrode 1A in FIG. 19A. . 20A shows a voltage difference when the phase of the applied voltage between the control electrodes 1A and 1B deviates by π, and FIG. 20B shows the phase difference of the applied voltage between the control electrodes 1A and 1B by π / 2. FIG. 20C shows the voltage difference when the control electrodes 1A and 1B are out of phase with each other by π / 4. From FIGS. 20 (a), 20 (b) and 20 (c), it is understood that the maximum voltage decreases as the phase shift decreases from π to π / 2, π / 4. Therefore, the effective range of the phase shift is preferably π / 2 to π.

By using the voltage application method of the present invention, the polarities of the voltages applied to the adjacent control electrodes and the opposing control electrodes are not constant as shown in FIG. Is less likely to adhere, it is possible to prevent deterioration of the electrorheological fluid,
Crosstalk does not occur.

[0055]

According to the present invention, by selectively driving the electrodes according to the recording pixels, the viscosity of the ink is changed and the ink itself forms a wall to dynamically form an ink channel. That is, at the time of non-printing, there is no nozzle in the liquid chamber, and the opening is formed in a slit shape and is very wide with respect to the opening corresponding to the pixel. Therefore, even if the ink in a part of the ink ejection port dries, clogging is less likely to occur,
Even if the ink changes in quality due to drying, it is unlikely to be affected.

By using the voltage application method of the present invention, the polarities of the voltages applied to the adjacent control electrodes and the control electrodes facing each other are not constant, so that bias of dispersed particles due to electrophoresis or adhesion to the electrodes does not easily occur. . Therefore, deterioration of the electrorheological fluid can be prevented. Further, since it is possible to prevent the viscosity of the ink channel from increasing due to the crosstalk, it is possible to realize a high resolution recording head.

[Brief description of drawings]

FIG. 1 is a side view schematically showing a recording head according to an embodiment of the present invention with a part thereof cut away.

FIG. 2 is a plan view schematically showing a part of the recording head shown in FIG. 1 by breaking it.

FIG. 3 is a front view showing a part of the recording head shown in FIG. 1 in a cutaway manner.

FIG. 4 is an explanatory diagram showing the operating principle of the recording head shown in FIG. 1.

5 is a graph showing the viscosity characteristics of the ink used in the recording head shown in FIG. 1 with respect to the voltage.

6 is a cross-sectional view schematically showing the arrangement of control electrodes in the recording head shown in FIG.

7 is a cross-sectional view of a recording head schematically showing an ink wall formed by the control electrode shown in FIG. 6 and a channel defined by the ink wall.

8 is a flowchart for explaining a printing operation in the recording head shown in FIG.

9 is a plan view schematically showing a process of manufacturing the recording head shown in FIGS. 1, 2 and 3. FIG.

FIG. 10 is a side sectional view schematically showing the recording head manufactured by the process shown in FIG.

FIG. 11 is a schematic diagram showing a recording apparatus incorporating the recording head shown in FIG.

12 is a block diagram schematically showing a control device of the recording apparatus shown in FIG.

FIG. 13 is a timing chart showing an example of drive timing at the time of recording operation in each part of the control device shown in FIG.

FIG. 14 is a timing chart showing another example of the drive timing at the time of recording operation in each part of the control device shown in FIG.

15 is a circuit diagram showing an outline of a voltage application circuit for applying a voltage to a control electrode in the viscosity control section shown in FIG.

16 is a waveform diagram showing signal waveforms in the circuit shown in FIG.

FIG. 17 is a schematic diagram for explaining a method of applying voltage to control electrodes in the recording apparatus of the present invention.

FIG. 18 is a waveform diagram showing an AC voltage waveform applied to a control electrode in an embodiment of the recording apparatus of the present invention.

FIG. 19 is a waveform diagram for explaining the timing of viscosity control and piezo element driving of the recording apparatus in the embodiment of the recording apparatus of the present invention.

FIG. 20 is a waveform diagram for explaining the phase shift of the voltage applied to the control electrodes in the embodiment of the recording apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Control electrode 1A ... Control electrode (upper side) 1B ... Control electrode (lower side) 2 ... Liquid chamber 3, 5 ... Channel B 4 ... Recording drive part 6 ... Piezo element 7, 8 ... Flow path wall 9 ... Droplet 10 ... Ink wall 11 ... Fine particles 12A ... Flat plate (upper side) 12B ... Flat plate (lower side) 13 ... ER ink 114 ... Recording head 115 ... Recording medium 116 ... Sensor 117 ... Platen roller

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location B41J 2/015 2/095 B41J 3/04 103 Z 104 B (72) Inventor Hisashi Tanaka Kawasaki City, Kanagawa Prefecture 70, Yanagimachi, Tokyo Inside Toshiba Intelligent Technology Co., Ltd.

Claims (7)

[Claims] 1. An ink having a plurality of first channels through which ink exhibiting an electrorheological effect is circulated and first and second inner surfaces facing each other, the ink being supplied through the first channel. A housing in which a slit-shaped opening for accommodating and ejecting the accommodated ink is formed, and a plurality of pairs of control electrodes arranged in a predetermined array so as to face each other on the first and second surfaces, respectively. A voltage applying means for applying a drive voltage to the control electrode pair, wherein an ink wall is formed by increasing the viscosity of the ink between the control electrode pair to which the voltage is applied, and the first channel is formed by the adjacent ink wall. And a voltage applying unit that communicates with the first channel to generate a second channel that allows the ink to flow to the opening, and an ink in the first channel that is provided in each of the first channels and that corresponds to print information. An ink jet recording apparatus, comprising: a pressure unit that applies a pressure to the ink to eject the ink in the corresponding second channel as an ink droplet from the opening. 2. An ink having a plurality of first channels through which ink exhibiting an electrorheological effect is circulated and first and second inner surfaces facing each other, the ink being supplied through the first channel. A housing in which a slit-shaped opening for accommodating and ejecting the accommodated ink is formed, and a plurality of pairs of control electrodes arranged in a predetermined array so as to face each other on the first and second surfaces, respectively. A voltage applying unit that applies a driving voltage to the control electrode pair to generate adjacent electric fields in different directions, and forms an ink wall by increasing the viscosity of the ink in the region to which the electric field is applied, And a voltage applying unit that communicates with the first channel by the ink wall to generate a second channel that allows the ink to flow to the opening, and a voltage applying unit that is provided in each of the first channels. And a pressurizing unit for applying pressure to the ink in the corresponding first channel to eject the ink in the corresponding second channel as an ink droplet from the opening. apparatus. 3. The voltage applying means applies a first voltage having a predetermined polarity to the control electrode pair, and applies a second voltage having a polarity opposite to the predetermined polarity to a control electrode pair adjacent thereto. Two
The inkjet recording apparatus according to claim 1, further comprising a voltage applying unit. 4. The voltage applying means applies a first AC voltage to the control electrode pair, and applies a first AC voltage to the control electrode pair adjacent thereto.
The inkjet recording apparatus according to claim 1, further comprising: two voltage applying means for applying a second AC voltage having a phase shifted from the AC voltage by π / 2 to π. 5. The phase of the voltage applied to the control electrode, the control electrode adjacent to the control electrode, and the control electrode facing the control electrode when AC is applied to the control electrode is deviated from the range of π / 2 to π. The inkjet recording method according to claim 1. 6. An ink wall is formed by increasing an electric field in a liquid chamber containing ink exhibiting an electrorheological effect to increase the viscosity of the ink by generating electric fields at a plurality of portions in the liquid chamber. A step of forming channels through which ink flows between the walls and selectively applying pressure to the ink supplied to the channels according to recording information to eject ink droplets from the corresponding channels to the outside of the liquid chamber Inkjet method. 7. The ink jet method according to claim 6, wherein the electric fields adjacent to each other have different directions of the electric fields.